Treating lactase deficiency with an active lactase

ABSTRACT

This invention relates to the administration of lactase from Aspergillus niger to lactase-deficient mammals.

United States Patent H91 H 1 1 Cayle 5] Feb. 27, 1973 [54] TREATING LACTASE DEFICIENCY WITH AN ACTIVE LACTASE [52] US. Cl ..424/94 75 I I [51] Int. Cl. ..A6lk 19/00 1 Thmdm [58] Field of Search ..424/94 [73] Assignee: Baxter Laboratories, Inc., Morton Grove, 111. Primary Examiner-Richard L. Huff [22] Filed June 15 1971 Att0rneyR0bert G. Pollock et a]. [21] Appl. No.: 153,423 [57] ABSTRACT Related Application Data This invention relates to the administration of lactase from Aspergillils niger to lactase-deiicient mammals. [62] Division of Ser. No. 8l2,348, April 1, 1969, Pat. No.

3,629,073. 2 Claims, N0 Drawings 1 TREATING LACTASE DEFICIENCY WITH AN ACTIVE LACTASE This application is a division of my application, Ser. No. 812,348, filed Apr. 1, 1969, now U.S. Pat. No. 3,629,073. v

This invention relates to lactase and, more particularly, to an acid-active, acid-stable lactase enzyme preparation suitable for the hydrolysis of lactose in acid media.

Whole milk normally contains about 5 percent lactose. Milk and products derived from milk which contain lactose, for example, butter, cheese, whey, non-fat milk solids, ice cream, and the like, have long been used as important nutrient components of human or animal diets. While whole milk constitutes a particularly large proportion of the normal infant ration, milk and milk containing products also provide a substantial complement to the usual adult diet.

Lactose, or milk sugar, is a disaccharide carbohydrate which is hydrolyzed during the digestive process to glucose and galactose. This hydrolysis is catalyzed by the enzyme lactase, or beta-galactosidase.

Although this enzyme is normally present in the intestinal juices and mucosa, recent investigations have shown that a significant portion of the human population is lactose intolerant or lactase deficient. Kern et al., J. Am. Med. Assn., Vol. 195, pp. 927-30 (1966). Consequently, there is a need for a dietary supplement of lactose-hydrolyzing lactase enzymes in these individuals.

'described in U.S. Pat. Nos. 2,681,858, 2,781,266and 2,809,] 13. The lactase enzyme preparations produced by these organisms generally have pH optimums on the alkaline side or in the weakly acid pH range of about 5-7. Yeasts, which are the primary source of commercial lactases, are known to produce lactases having pH optimums of about 7. Most of these conventional lactase enzyme preparations contain other enzymes in admixture therewith, for example, proteases and amylases, which are the predominant components in the mixture.

1n the stomach the gastric fluid provides strongly acidic conditions in the pH range of about 1 to 3. Therefore, the activity of lactase enzyme preparations which are generally highly effective in alkaline or weakly acidic media are for the most part destroyed or inactivated when contacted with the'gastric fluid.

' Accordingly, it is an object of the present invention to provide an acid-active, acid-stable lactase enzyme preparation suitable for the hydrolysis of lactosein acid media.

It is another object of the present invention to provide an acid-active, acid-stable enzyme preparation suitable for oral ingestion.

it is still another object of the present invention to provide a method for the hydrolysis of lactose in milk and milk products. I l

It is a further object of the present invention to provide a method of reducing lactase deficiency in an animal.

Other objects and advantages of the present invention will be apparent to those skilled in the art after reading this specification and the appended claims.

In accordance with the present invention, an acid-active, acid-stable lactase enzyme preparation suitable for the hydrolysis of lactose in acid media is provided by growing a culture of Asperguillus niger and separating therefrom a lactase enzyme preparation which is stable in the range of pH 2-9, exhibits at least about percent of its activity at pH 2.5-5.0 and contains at least about 50,000 Lactase Units (LU) per gram of enzyme preparation.

In the copending application of Harvey and Viebrock, U.S. Ser. No. 812,347, filed Apr. 1, 1969, a method for the production of an acid-active, acid-stable lactase enzyme from Aspergillus niger as described herein is disclosed. This method comprises growing a culture of Aspergillus niger under aerobic fermentation conditions, extracting the growth product with water, slurrying the extract with a hydrated aluminum silicate adsorbent at a pH of from about 3 to about 6to adsorb an active lactase component, separating the precipitate and releasing the active lactase component therefrom by adjusting the pH to about 7 to about 8 with an aqueous alkaline reagent. The disclosure of said method in. said co-pending application is incorporated herein by reference.

As used herein, the term Lactase Unit (LU) is defined as that quantityof enzyme which will produce 10' moles of o-nitrophenol (GNP) per minute, at 37 C, pH 4.4, at a concentration of o-nitrophenyl-beta-D galactoside (ONPG) of 0.0005 M i The assay procedure employed for determining lactase activity is as follows:

DETERMINATION OF -oA AcTosm sa (LACTASE) ACTIVITY phosphate- 139.1l mg. NP-in 50 ml. ethanol. Dilute to 1,000m1. with distilled water. Procedure A.'A reference curve is prepared with increments of o-nitrophenol. Dilute one part of the ON? stock solution with nine parts of the 0.01 M buffer. Add from 1 to 10ml. of the diluted solution, in 1 ml. (0.5 Lactase Unit) increments, to a series of 10 test tubes, and make each tube to a final volume of 10 ml. with buffer. Add] ml. of carbonate solution to each tube. Determine absorbance in 'a colorimeter at 400-420 mp1. If a Klett instrument is used, employ No. 42 filter. Plot colorimeter values against moles of ONP per test tube. Since 1O" moles of GNP produced under the conditions of the assay correspond to 5 Lactase Units (as hereinbefore defined), the plot can be made of colorimeter readings directly against Lactase Units.

B. The test enzyme dissolved in buffer in a total volume of 9 ml. and containing from 1-5 Lactase Units is added to a test tube. Enzyme solution and substrate are atempered separately at 37 C. Add 1 ml. of substrate to the tube containing the enzyme, mix well, and incubate for exactly 20 minutes. Add 1 ml. of carbonate solution and read in a colorimeter against a substrate blank incubated without enzyme, but otherwise treated in the same manner. If a hazy or colored enzyme solution is used, an enzyme blank must be employed. This can be prepared by incubating the substrate as above, and adding the enzyme after the addition of carbonate solution.

Calculations of Lactase Activity The activity of the enzyme test solution is determined from the reference curve. The LU of the enzyme preparation is determined by dividing the units in the test by the grams of enzyme in the test.

EXAMPLE If 0.1 mg. of enzyme in the test solution is responsible for the production of 10' moles of GNP under the conditions of the test, this test solution contains 5 LU.

LU of pre aration 5 LU/l X 10' 50,000 LU/ P g g The Aspergillus niger used in this invention is a common and well-known species of microorganism, described in detail by Thom and Raper, Manual Of The Aspergilli, published by Williams & Wilkins Co., Baltimore, 1945, at pages 214 to 240, which are incorporated herein by reference for background information. Illustrative examples of this fungal species are on deposit in stock cultures and available to the public in the permanent collection of the Northern Utilization and Research Division, Agricultural Research Service, U.S. Department of Agriculture, Peoria, 111., under accession numbers NRRL 326, NRRL 330, NRRL 334, NRRL 337, NRRL 346 and NRRL 697. Other illustrative examples of this organism are available to the scientific community and other members of the public from the American Type Culture Collection, Rockville, Md., under the deposit numbers ATCC 13,496 ATCC 13,497. It will be understood that the present invention is not limited to the use of these representative examples of Aspergillus niger which are set forth for purposes ofillustration and not limitation.

For purposes of oral ingestion, it is desirable to provide the herein-defined lactase enzyme preparation for administration in unit dosage form such as, for example, tablets, pills, capsules, powders, wafers, cachets and granules, or solutions, suspensions and dispersions in aqueous or non-aqueous vehicles, including syrups, elixers, and the like.

In preparing solid compositions of the lactase enzyme preparation of this invention, for example, tablets, the active lactase enzyme preparation preferably is mixed with conventional solid fillers or carriers such as cornstarch, talc, calcium phosphate, calcium sulfate, calcium stearate, magnesium stearate,

steric acid, glyceryl monoand distearate, sorbitol, mannitol, gelatin, natural or synthetic gums such as carboxymethyl cellulose, methyl cellulose, alginate, dextran, acacia gum, karaya gum, locust bean gum, tragacanth and the like diluents, binders, lubricants, disintegrators, coloring and flavoring agents.

Suitable liquid forms of the novel composition of this invention can be prepared by incorporating the active lactase enzyme preparation in aqueous or non-aqueous dispersions, suspensions, and solutions with conventional liquid carriers such as, for example, glycerol and edible glycols, edible oils such as cottonseed oil, soybean oil, corn oil, peanut oil, safflower oil and other triglyceride oils, dispersing or suspending agents such as the aforesaid natural and synthetic gums and various other diluents and vehicles.

Any conventional method of tableting, encapsulating, microencapsulating, andthe like can be used for preparing unit oral dosage forms of the lactase enzyme preparation of the invention. Since the lactase enzyme preparation of this invention is both active and stable in the low acid pH range approximating the acidity of the gastric fluid, it is not necessary to use enteric coating procedures and the like to protect the active lactase enzyme in the digestive system. However, in certain cases it may be desirable to enterically coat the oral dosage form of the lactase enzyme preparation. Accordingly, conventional methods of enteric coating are also contemplated within the scope of this invention.

The quantity of lactase enzyme preparation employed in the total oral dosage form can vary within wide limits, depending in part upon the lactase activity of the particular enzyme preparation, the magnitude of the lactase deficiency or lactose intolerance in the particular subject requiring the dietary supplement of lactase and the particular dietary characteristics of these subjects.

In general, the amount of lactase enzyme preparation in the unit oral dosage form preferably is sufficient to provide that amount of lactase enzyme needed to hydrolyze the lactose normally present or normally produced in the subject requiring the lactase supplement.

The lactase enzyme preparation of this invention can also be produced in powdered or granular form for direct admixture with the normal food and feed products used by the subjects requiring the dietary supplement of lactase. For example, in the case of an infant requiring a dietary supplement of lactase, a suitable amount of the lactase enzyme preparation of this invention in a powdered or granular form can be added directly to the milk or other food regimen of that infant in any suitable amount. 1n the case of an animal that normally requires a dietary regiment of whey, the lactase enzyme preparation of this invention in a powdered or granular form can be added directly to this whey.

In accordance with another aspect of the invention, the acid-active, acid-stable lactase enzyme preparation derived from Aspergillus niger is used for removal of the lactase initially present in acid whey, such as produced during cottage cheese manufacture.

Other methods of employing the lactase enzyme preparation of this invention will be apparent to those skilled in the art.

The following examples will further illustrate the present invention although the invention is not limited to these specific examples. All percentages and parts herein are on a weight basis unless otherwise specified.

EXAMPLE 1 A lactase enzyme preparation having an activity of at least 50,000 LU per gram is prepared as follows:

To 100 parts of wheat bran was added 60 parts of 0.2N hydrochloric acid containing 0.62 ppm of ZnSO 0.62 ppm of FeSO and 0.88 ppm CuSO,. The mixture was sterilized with steam and, after cooling, was inoculated with a sporulated inoculum of Aspergillus niger. The inoculated bran was maintained at a temperature of 30 C by passing moist air through the mixture until testing indicated the presence of substantial quantities of lactase after growth for 4 days.

An aqueous extract of the growth product was prepared by washing the above mixture with four volumes of water. The extract was concentrated by evaporation to a specific gravity of 1.1.

A suitable quantity of the above aqueous extract was treated with calcium hydroxide and the pH brought to 6.5-6.8. The mixture was filtered after stirring for approximately 30 minutes.

A percent aqueous bentonite slurry was added to the above filtrate in an amount of about 2.5-3 percent by weight of the filtrate. The pH of the mixture was adjustedto 3.9-4.1 and stirred for 30 minutes, after which time it was filtered. The filter cake was sparged with a 45 percent aqueous acetone solution.

The filter cake was then dispersed in a quantity of water equal to approximately twice the cake weight and ammonium hydroxide was added until the pH of the mixture was in the range of 6.9-7.2. After stirring for 30 minutes, the mixture was filtered.

The filtrate was then evaporated to a dry product by spray drying.

The A. niger lactase enzyme preparation produced in accordance with the above method has an activity of at least 50,000 LU/gram, and enzyme preparations can be obtained with activities of about 500,000 to 600,000 LU/gram by this method, depending upon the activity and purity of the starting inoculum of Aspergillus niger.

EXAMPLE 2 TABLE I Effect of pH on Relative Activity of A. niger Lactase at 37C and 55C Substrate Lactose Relative Activity Percent pH 37C 55C TABLE II Effect of Temperature on Relative Activity of A. niger Lactase at pH 3.5 Substrate Lactose Temperature C Relative Activity-present Stability as a Function of pH The stability of A. niger lactase as a function of pH was established. An aqueous solution of the enzyme was incubated at a concentration of 0.1percent, at various pH values and at 37 C for one hour. The solution was then adjusted to pH 4.3 and assayed on lactose to establish the residual activity. The data in Table 111 were obtained:

TABLE III The Stability of the A. niger Lactase in Solution at Various pI-l Values Time 1 Hour at 37C pl-l Activity Retained Aqueous solutions of the A. niger lactase retain full activity after exposure at 37 C for 1 hour between pH 3 and pH 7.5, or at least percent between pl -l 2.2 and pH 8.3, and at least 50 percent activitybetween pH 1.6and pH 8.9. Stability as a Function of Temperature The stability of the A. niger lactase as a function of temperature was established. An aqueous solution of the enzyme was incubated at a concentration of 0.1 percent at the test temperature for 1 hour at pH 5.2 (in distilled water) and at pH 3.5 (in 0.01M acetate and then assayed with ONPG at 37 C, at pH 3.5. The following data were obtained:

TABLE IV Stability of A. niger Lactase in Solution at Various Temperature Time 1 Hour Activity Retained Temperature "C pH 3.5 pH 5.2

At least 97 percent of the activity of the A. niger lactase is retained at all temperatures at pH 5.2, and the maximum loss at pH 3.5 at 55 C is 16 percent.

EXAMPLE 3 The activity and stability of the A. niger lactase enzyme preparation of Example 1 was compared with the activity and stability of a commercially available lactase enzyme preparation derived from S. fragilis as follows:

Stability as a Function of PH The stability of the A. niger lactase and S. fragilis lactase as a function of pH was established and compared. Each enzyme was incubated at a concentration of 0.1 percent, at the test pH, at 37 C for 1 hour. The A. niger lactase was then adjusted to pH 4.3 and assayed on lactose to establish the residual activity. The S. fragilis enzyme was incubated in the presence of 0.1M phosphate in view of the reports in the literature (see reference) (*Davies, J. Gen. MicroboiL, Vol. 37, p. 81 et seq. (1964).) that this enzyme is stable in solution only in the presence of this salt. It was when assayed at pH 7 on ONPG. The following data were obtained:

When the above data are plotted with activity retained as a function of the incubation pH, it is seen that the A. niger lactase retains 100 percent of its activity after exposure at 37 C for 1 hour between pH 3 and 7.5, or at least 90 percent between pH 2.2 and 8.3, and at least 50 percent of its activity between pH 1.6 and 8.9, whereas the S. fragilis enzyme retains 100 percent of its activity only at pH 7, and 50 percent of its activity under similar conditions between pH 5.2 and 8. Stability as a Function of Temperature The stability of the A. niger lactase and S. fragilis lactase as a function of temperature was established and compared. Each enzyme was incubated at a concentration of 0.1 percent at the test temperatures for 1 hour. The A. niger lactase was incubated at pH 5.2 in distilled water, and pH 3.5 in 0.01M acetate. The S. fragilis enzyme was incubated at pH 7.3 in distilled water and pH 7.0 in 0.1M phosphate. Both enzymes were assayed on ONPG at 37 C, at pH 3.5 with the A. niger lactase and at pH 7 with the S. fragilis enzyme. The following data were obtained:

TABLE VI Activity Retained TemperatureA. Niger Lactase S. fragilis Lactase pH 3.5 pH 5.2 pH7.0(PO pH7.3

When the above data are plotted with activity retained as a function of incubation temperature, it is seen that at least 97 percent of the activity of the A. niger lactase is retained at all temperatures at pH 5.2, and the maximum loss at pH 3.5 at 55 C is 16 percent. On the other hand, the S. fragilis enzyme loses over percent of its activity at 45 C and 100 percent of its activity at 55 C, despite the presence of 0.1M phosphate. In the absence of the stabilizing salt, over 60 percent of the activity is lost at 35 C, and progressively more is lost at the higher temperatures.

EXAMPLE 4 To 100 ml of an acid whey, at a pH of 4.3, containing 4.96 grams of lactose, was added 64 mg of a lactase enzyme preparation (prepared in accordance with Example 1) containing a total of 36,800 Lactase Units. This was allowed to incubate at 55 C, and samples of the hydrolyzate were withdrawn periodically and the extent of lactose hydrolysis determined as a function of time. Table V11 shows the data obtained:

present in acid whey can be hydrolyzed within 30 minutes at 55 C, and percent can be removed within 3% hours, by employment of the lactase enzyme preparation of the present invention.

EXAMPLE 5 An aqueous oral suspension containing in each 5 ml., 0.5 gram of the lactase enzyme preparation produced in accordance with Example 1 is prepared from the following materials:

Lactase (25,000 LU) 0.5 gram Glycerol 1.5 ml

Tragacanth powder 0.0] gram Orange oil flavor 0.001 gram Water, q.s. to 5 ml EXAMPLE 6 A lot of 100 tablets for oral use, each containing 0.5

gram of the lactase enzyme preparation produced in accordance with Example 1 is prepared from the following materials:

Lactase (50,000 LU) 1 gram Cornstarch 45 grams Magnesium stearate 1 gram Gelatin Total: 50 grams 3 grams the foregoing specification and appended claims without departing from the spirit and scope of the invention. All such examples, modifications and variations are included within the scope of the appended claims.

What is claimed is:

1. The method of reducing lactase deficiency in mammals comprising orally administering to a lactase deficient mammal an amount of lactase enzyme sufficient to hydrolyze the undigested lactose normally present in said mammal, said lactase enzyme being an acid-active, acid-stable lactase enzyme preparation obtained from the growth product of a culture of Aspergillus niger by absorption with hydrated aluminum silicate at a pH of from about 3 to about 6 followed by release of the enzyme preparation by adjustment to a pH of from about 7 to about 8, said lactase enzyme preparation being stable in the range of pH 2-9, exhibiting at least about percent of its activity at pH 2.5-5.0 and at 37 C and containing at least 50,000 Lactase Units per gram of enzyme preparation.

2. The method of claim 1 in which the enzyme preparation is administered in admixture with an edible carrier. 

2. The method of claim 1 in which the enzyme preparation is administered in admixture with an edible carrier. 